Semiconductor device with a semiconductor chip connected in a flip chip manner

ABSTRACT

A semiconductor device ( 1,21 ) includes a solid state device ( 2,22 ), a semiconductor chip ( 3 ) that has a functional surface ( 3   a ) on which a functional element ( 4 ) is formed and that is bonded on a surface of the solid state device with the functional surface thereof facing the surface of the solid state device and while maintaining a predetermined distance between the functional surface thereof and the surface of the solid state device, an insulating film ( 6 ) that is provided on the surface ( 2   a,    22   a ) of the solid state device facing the semiconductor chip and that has an opening ( 6   a ) greater in size than the semiconductor chip when the surface of the solid state device facing the semiconductor chip is vertically viewed down in plane, and a sealing layer ( 7 ) that seals a space between the solid state device and the semiconductor chip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/782,580,filed on Mar. 1, 2013, which was a continuation of application Ser. No.10/594,561, filed on Sep. 27, 2006, now issued as U.S. Pat. No.8,405,227 on Mar. 26, 2013. Furthermore, this application claims thebenefit of priority of Japanese application 2004-282017, filed Sep. 28,2004. The disclosures of these prior U.S. and Japanese applications areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductor device that has asemiconductor chip connected in a flip chip manner.

2. Description of Related Art

To realize a size reduction and high-density packaging of asemiconductor device, attention has been paid to a flip chip connectionstructure in which a semiconductor chip is connected to a solid statedevice while causing a functional surface of the semiconductor chip onwhich a functional element 54 is formed to face the solid state device.

FIG. 4 is a diagrammatic sectional view of a semiconductor device havinga flip chip connection structure. This semiconductor device 51 includesa wiring board 52 and a semiconductor chip 53 connected to a surface 52a of the wiring board 52 while causing a functional surface 53 a of thesemiconductor chip 53 to face the surface 52 a of the wiring board 52.

A rectangular connection pad 58 is formed on the surface 52 a of thewiring board 52. The wiring board 52 and the semiconductor chip 53 arebonded and electrically connected together with a predetermined intervaltherebetween by means of a connecting member 55 connected to theconnection pad 58. A solder resist film 56 that has a thickness smallerthan an interval between the surface 52 a of the wiring board 52 and thefunctional surface 53 a of the semiconductor chip 53 is formed on thesurface 52 a.

The solder resist film 56 has a rectangular opening 56 a by which theconnection pad 58 is exposed. As shown in FIG. 5, the opening 56 a isgreater in size than the connection pad 58 when viewed in plane. Theconnecting member 55 is connected to the connection pad 58 in theopening 56 a.

A slight gap is formed between the surface of the solder resist film 56and the functional surface 53 a of the semiconductor chip 53. This gapis sealed with an underfill layer 57. The underfill layer 57 is formedsuch that the wiring board 52 and the semiconductor chip 53 are bondedtogether, and then a liquid underfill material is injected therebetween.

In more detail, after the wiring board 52 and the semiconductor chip 53are bonded together, a dispenser 60 is disposed near the outerperipheral part of the semiconductor chip 53 as shown in FIG. 6A,whereafter a liquid underfill material 57P is poured between the surfaceof the solder resist film 56 and the functional surface 53 a of thesemiconductor chip 53 from the dispenser 60. Capillarity causes theunderfill material 57P to enter and spread between the surface of thesolder resist film 56 and the functional surface 53 a of thesemiconductor chip 53 as shown in FIG. 6B. When the whole area betweenthe surface of the solder resist film 56 and the functional surface 53 aof the semiconductor chip 53 is filled with the underfill material 57P,the dispenser 60 stops discharging the underfill material 57P.Thereafter, the underfill material 57P is hardened, whereby theunderfill layer 57 is obtained (see Chee Choong Kooi and six others,“Capillary Underfill and Mold Encapsulation Materials for Exposed DieFlip Chip Molded Matrix Array Package with Thin Substrate”, 2003Electronics Packaging Technology Conference, pp. 324-330).

However, a level difference locates between the inside and the outsideof the opening 56 a, and a space over the opening 56 a is restricted bythe semiconductor chip 53. Therefore, disadvantageously, when theunderfill material flows into the opening 56 a, air that exists aroundthe periphery of the opening 56 a (i.e., exists in a portion having thelevel difference) is taken into the underfill material withoutsufficiently going out therefrom, and, as a result, a so-called void 61is generated in the underfill layer 57. For example, if a void isgenerated in the underfill layer 57, a crack will appear in theunderfill layer 57 at a reflow step, thus causing a decrease inreliability of the semiconductor device.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor devicehaving a structure capable of preventing a void from occurring in asealing layer.

The semiconductor device according to the present invention includes asolid state device; a semiconductor chip that has a functional surfaceon which a functional element is formed and that is bonded on a surfaceof the solid state device with surface thereof to face a surface of thesolid state device while maintaining a predetermined distance betweenthe functional surface thereof and the surface of the solid statedevice; an insulating film that is provided on the surface of the solidstate device facing the semiconductor chip and that has an openinggreater in size than the semiconductor chip when the surface of thesolid state device facing the semiconductor chip is vertically vieweddown in plane; and a sealing layer that seals a space between the solidstate device and the semiconductor chip.

According to this invention, the opening of the insulating film isformed to be greater in size than the semiconductor chip when thesurface of the solid state device facing the semiconductor chip isvertically viewed down in plane. In other words, the opening of theinsulating film is formed such that the semiconductor chip completelyfalls within the opening when the surface of the solid state devicefacing the semiconductor chip is vertically viewed down in plane.Therefore, a level difference caused by the opening of the insulatingfilm can be prevented from locating in a gap between the solid statedevice and the semiconductor chip, and a space over the periphery of theopening can be prevented from being restricted by the semiconductorchip.

Therefore, in a step of producing this semiconductor device, a void canbe prevented from being generated that results from taking air into aliquid sealing resin when a gap between the solid state device and thesemiconductor chip is filled with the liquid sealing resin in order toform the sealing layer after forming the insulating film and bonding thesolid state device and the semiconductor chip together. As a result, thereliability of the semiconductor device can be improved.

Preferably, the distance between the outer periphery of thesemiconductor chip and the edge of the opening of the insulating film is0.1 mm or more when the surface of the solid state device facing thesemiconductor chip is vertically viewed down in plane.

The solid state device may be a wiring board formed by being wired on aninsulating substrate, or may be a semiconductor substrate.

The insulating film may be a solder resist. In this case, it is possibleto prevent an electric short circuit in an area covered with the solderresist.

The sealing layer may be provided in such a way as to fill the inside ofthe opening therewith. If so, in the solid state device, a part exposedfrom the opening of the insulating film can be protected with thesealing layer.

The aforementioned object, other objects, features, and advantageouseffects of the present invention will become apparent from the followingdescription of embodiments given with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of a semiconductor deviceaccording to a first embodiment of the present invention.

FIG. 2A to FIG. 2D are diagrammatic sectional views for explaining amethod for producing the semiconductor device of FIG. 1.

FIG. 3 is a diagrammatic sectional view of a semiconductor deviceaccording to a second embodiment of the present invention.

FIG. 4 is a diagrammatic sectional view showing a structure of aconventional semiconductor device that has a semiconductor chipconnected in a flip chip manner.

FIG. 5 is a diagrammatic plan view in which a connection surface of awiring board of FIG. 4 is vertically viewed down.

FIG. 6A and FIG. 6B are diagrammatic sectional views for explaining amethod for producing the semiconductor device of FIG. 4.

FIG. 7 is a plan view of a semiconductor device according to the firstand second embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a diagrammatic sectional view of a semiconductor deviceaccording to a first embodiment of the present invention.

This semiconductor device 1 includes a wiring board 2 and asemiconductor chip 3 connected to the wiring board 2 while causing afunctional surface 3 a of the semiconductor chip 3 to face a surface 2 aof the wiring board 2. A rectangular connection pad (see FIGS. 2C and2D) is formed on the surface 2 a of the wiring board 2. The wiring board2 and the semiconductor chip 3 are bonded and electrically connectedtogether by means of a connecting member 5 connected to the connectionpad, with a predetermined interval between the wiring board 2 and thesemiconductor chip 3.

A solder resist film 6 that has a thickness smaller than the intervalbetween the surface 2 a of the wiring board 2 and the semiconductor chip3 is formed on the surface 2 a. This solder resist film 6 serves toprevent an electric short circuit from occurring between wires formed onthe surface of the wiring board 2. The solder resist film 6 has anopening 6 a greater in size than the semiconductor chip 3 when thesurface 2 a is vertically viewed down in plane. In other words, thesolder resist film 6 has an opening 6 a large enough to allow thesemiconductor chip 3 to completely fall within the opening 6 a when thesurface 2 a is vertically viewed down in plane. Accordingly, the solderresist film 6 does not exist in a gap G between the wiring board 2 andthe semiconductor chip 3 (i.e., in an area lying between the wiringboard 2 and the semiconductor chip 3 and overlapping with thesemiconductor chip 3 when the surface 2 a is vertically viewed fromabove, as in FIG. 7). Gap G is thus in a well that is between the wiringboard 2 and the semiconductor chip 3, the well having sidewalls withinthe opening 6A (see FIG. 2D) of the solder resist film 6.

The distance D between the outer periphery of the semiconductor chip 3and the edge of the opening 6 a of the solder resist film 6 is set at0.1 mm or more when the surface 2 a is vertically viewed down in plane.

An underfill layer 7 is provided in the gap G between the wiring board 2and the semiconductor chip 3 and in the neighborhood of the gap G. Theunderfill layer 7 is formed so as to fill the opening 6 a of the solderresist film 6 therewith. The underfill layer 7 serves to seal the gap Gtherewith and to protect the functional surface 3 a, the connectingmember 5, and an exposed part of the surface 2 a exposed from theopening 6 a.

An end electrode 8 that is electrically connected to the connectingmember 5 through a wire (not shown) is formed at each end of the wiringboard 2. The end electrode 8 leads from the surface 2 a of the wiringboard 2 to an external connection surface 2 b which is the surface onthe side opposite the surface 2 a via the end face. In the end electrode8, the semiconductor device 1 can establish an electric connection withother wiring boards (mounting boards).

FIGS. 2A to 2D are diagrammatic sectional views for explaining a methodfor producing the semiconductor device 1 shown in FIG. 1. Thesemiconductor device 1 can be obtained such that the semiconductor chip3 is bonded to the wiring board 2 while causing the functional surface 3a of the semiconductor chip 3 to face the surface 2 a of the wiringboard 2, whereafter an underfill material 7P is injected into theopening 6 a of the solder resist film 6, and the underfill material 7Pis hardened, whereby the underfill layer 7 is formed.

In more detail, a substrate 15 in which a plurality of wiring boards 2are formed is first prepared.

Thereafter, a liquid, photosensitive solder resist film 6 is applied(for example, according to a spin coat method) or is printed onto thewhole of a surface 15 a of the substrate 15 (i.e., a surfacecorresponding to the surface 2 a of the wiring board 2), and the opening6 a greater in size than the semiconductor chip 3 is formed by exposureand development.

Thereafter, a semiconductor chip 3 having a projection electrode (bump)18 connected to an electrode of a functional element 4 is prepared. Theprojection electrode 18 includes a solder material.

Thereafter, the substrate 15 is kept substantially horizontal whiledirecting the surface 15 a thereof upward. The semiconductor chip 3 isheld while the surface opposite the functional surface 3 a is beingabsorbed by a bonding tool 19 equipped with a heater for heatingtherein. The semiconductor chip 3 is caused to face the surface 15 a ofthe substrate 15 while directing the functional surface 3 a downward.FIG. 2A shows this state.

Thereafter, the projection electrode 18 of the semiconductor chip 3 ispositionally adjusted for the contact with a connection pad 16 of thesubstrate 15, whereafter the bonding tool 19 is lowered so as to bondthe semiconductor chip 3 with the substrate 15. In this case, thesemiconductor chip 3 is heated by the bonding tool 19, and the soldermaterial of the projection electrode 18 is melted by that heat, wherebythe projection electrode 18 and the connection pad 16 are bondedtogether. As a result, the connecting member 5 by which the substrate 15and the semiconductor chip 3 are mechanically bonded together is formed.The wiring formed on the surface 15 a of the substrate 15 iselectrically connected to the functional element 4 of the semiconductorchip 3 by means of the connecting member 5. As shown in FIG. 1, thefunctional element 4 is not formed in an end portion or periphery of thefunctional surface 3 a of the semiconductor chip 3, so functionalelement 4 is formed only on a part of the functional surface of thesemiconductor chip.

Thereafter, a dispenser 10 is disposed over the periphery of the opening6 a of the solder resist film 6, whereafter the underfill (sealinglayer) material 7P is injected from the dispenser 10 into the opening 6a (see FIG. 2B).

The underfill material 7P enters the gap G between the substrate 15 andthe semiconductor chip 3, and spreads on the surface 2 a in the gap G bycapillarity (see FIG. 2C, wherein the direction in which the underfillmaterial 7P spreads is indicated by arrow “A”). The underfill material7P is discharged from the dispenser 10 by a suitable quantity. When thegap G and the inside of the opening 6 a of the solder resist film 6 arefilled with the underfill material 7P, the dispenser 10 stopsdischarging the underfill material 7P. Thereafter, a process forhardening the underfill material 7P is performed, and the underfilllayer 7 is formed in the opening 6 a. As shown in FIG. 2D, the underfillor sealing layer 7P does not cover an upper surface of the solder resistfilm or insulating film 6 and the sealing layer covers a side face ofthe semiconductor chip 3 up to a middle portion thereof.

Thereafter, the substrate 15 is cut into wiring boards 2 (the cuttingposition is indicated by reference character “C” in FIG. 2A), and theend electrode 8 is formed at each end of the wiring board 2, thus thesemiconductor device 1 of FIG. 1 is obtained.

As described above, the opening 6 a of the solder resist film 6 isformed such that the semiconductor chip 3 completely falls within theopening 6 a when the surface 15 a is vertically viewed down in plane.Accordingly, a level difference caused by the opening 6 a of the solderresist film 6 can be prevented from locating in the gap G between thesubstrate 15 and the semiconductor chip 3, and a space over theperiphery of the opening 6 a can be prevented from being restricted bythe semiconductor chip 3.

Therefore, a void can be prevented from being generated that resultsfrom taking air into the underfill material 7P when the liquid underfillmaterial 7P is injected into the gap G between the substrate 15 and thesemiconductor chip 3. As a result, the reliability of the thus obtainedsemiconductor device 1 can be improved.

Since the underfill layer 7 has no void, a crack caused by a void doesnot occur even when the semiconductor device 1 is bonded with anotherwiring board according to, for example, a reflow method.

FIG. 3 is a diagrammatic sectional view of a semiconductor deviceaccording to a second embodiment of the present invention. In FIG. 3,the same reference character as in FIG. 1 is given to an elementcorresponding to each element of FIG. 1.

This semiconductor device 21 includes a wiring board 22 and asemiconductor chip 3 connected to the wiring board 22 while causing afunctional surface 3 a of the semiconductor chip 3 to face a surface 22a of the wiring board 22.

A solder resist film 6 is formed on the surface 22 a of the wiring board22. The solder resist film 6 has an opening 6 a that is greater in sizethan the semiconductor chip 3, in other words, that is formed such thatthe semiconductor chip 3 completely falls within the opening 6 a whenthe surface 22 a is vertically viewed down in plane.

In the wiring board 22, metallic balls 23 are provided on an externalconnection surface 22 b opposite the surface 22 a. The metallic balls 23are re-wired inside the wiring board 22 and/or on the surface of thewiring board 22, and are electrically connected to a connecting member 5on the side of the surface 22 a. The semiconductor device 21 can bebonded with other wiring boards (mounting boards) via the metallic balls23.

When the semiconductor device 21 is produced, the same producing methodas above (see FIGS. 2A to 2D) can be carried out using a substrate onwhich regions corresponding to a plurality of wiring boards 22 aredensely formed, instead of the substrate 15. The metallic balls 23 maybe bonded with this substrate before cutting the substrate into piecesof the wiring board 22, or may be bonded with the wiring boards 22 aftercutting the substrate into pieces of the wiring board 22.

Although the embodiments of the present invention have been described asabove, the present invention can be embodied in other forms. Forexample, two or more semiconductor chips 3 may be connected to thewiring boards 2 and 22 in a flip chip manner. In this case, the solderresist film 6 can have at least one opening 6 a that completely includeseach semiconductor chip 3 when the surfaces 2 a and 22 a are verticallyviewed down in plane.

The embodiments of the present invention have been described in detail.However, these are merely concrete examples used to clarify thetechnical contents of the present invention, and the present inventionshould not be understood while being limited to these examples, and thespirit and scope of the present invention are limited only by the scopeof the appended claims.

What is claimed is:
 1. A semiconductor device comprising: a wiring boardhaving a surface, a semiconductor chip having a functional surface, aconnecting member provided between the surface of the wiring board andthe functional surface of the semiconductor chip, the connecting memberextending a distance between the surface of the wiring board and thefunctional surface of the semiconductor chip, a sealing material thatseals a gap space between the wiring board and the semiconductor chip,and an electrode formed as part of the wiring board and arranged outsideof an outer periphery of the sealing material, wherein a lateraldistance between an outer periphery of the semiconductor chip and theouter periphery of the sealing material is between 0.1 mm and a lateraldistance from the outer periphery of the semiconductor chip to theelectrode.
 2. The semiconductor device according to claim 1, wherein theconnecting member mechanically bonds the wiring board and thesemiconductor chip together.
 3. The semiconductor device according toclaim 1, wherein the connecting member electrically connects a wire inthe wiring board to a functional part of the functional surface.
 4. Thesemiconductor device according to claim 1, wherein the distance betweenthe surface of the wiring board and the functional surface of thesemiconductor chip is an interval defining the gap space between thewiring board and the semiconductor chip.
 5. The semiconductor deviceaccording to claim 1, wherein the wiring board and the semiconductorchip are electrically connected together.
 6. The semiconductor deviceaccording to claim 1, further comprising an insulating layer providedover a portion of the surface of the wiring board and having a boundaryoutside the outer periphery of the semiconductor chip.
 7. Thesemiconductor device according to claim 6, wherein the sealing materialextends laterally beyond the periphery of the semiconductor chip andwithin the boundary of the insulating layer.
 8. The semiconductor deviceaccording to claim 1, wherein the electrode is electrically connected tothe connecting member.
 9. The semiconductor device according to claim 1,further comprising additional connecting members provided between thesurface of the wiring board and the functional surface of thesemiconductor chip, the additional connecting members extending thedistance between the surface of the wiring board and the functionalsurface of the semiconductor chip wherein the distance between thesurface of the wiring board and the functional surface of thesemiconductor chip is an interval defining the gap space between thewiring board and the semiconductor chip.
 10. The semiconductor deviceaccording to claim 1, wherein the sealing material at least partiallycovers a side surface of the semiconductor chip.
 11. A semiconductordevice comprising: a substrate including: an upper surface; and a welldisposed in the upper surface, the well including a surface of thesubstrate; a semiconductor chip having a functional surface, aconnecting member provided between the surface of the substrate and thefunctional surface of the semiconductor chip, the connecting memberextending over a distance between the surface of the substrate and thefunctional surface of the semiconductor chip, a sealing layer that sealsa gap space between the substrate and the semiconductor chip, andextending laterally beyond an outer periphery of the semiconductor chip;an insulating layer as part of a portion of the upper surface, theinsulating layer having a boundary outside the outer periphery of thesemiconductor chip; wherein a lateral distance between the outerperiphery of the semiconductor chip and an outer periphery of thesealing layer is between 0.1 mm and a lateral distance from the outerperiphery of the semiconductor chip and the side wall of the well. 12.The semiconductor device according to claim 11, wherein the connectingmember mechanically bonds the substrate and the semiconductor chiptogether.
 13. The semiconductor device according to claim 11, whereinthe substrate comprises a wiring board and the connecting memberelectrically connects a wire in the wiring board to a functional part ofthe functional surface.
 14. The semiconductor device according to claim11, wherein the distance between the surface of the substrate and thefunctional surface of the semiconductor chip is an interval defining thegap space between the surface of the substrate and the semiconductorchip.
 15. The semiconductor device according to claim 11, wherein thewell has a set of sidewalls defining an opening having dimensions largerthan dimensions of the outside periphery of the semiconductor chip andoutside a periphery of the boundary of the insulating layer.
 16. Thesemiconductor device according to claim 15, wherein the set of sidewallsare comprised of the boundary of the insulating layer outside the outerperiphery of the semiconductor chip.
 17. The semiconductor deviceaccording to claim 11, wherein a depth of the well is less than thedistance between the surface of the substrate and the functional surfaceof the semiconductor chip.
 18. The semiconductor device according toclaim 15, further comprising an electrode formed as part of thesubstrate arranged outside of the set of sidewalls of the well.
 19. Asemiconductor device comprising: a wiring board having a surfaceportion; a semiconductor chip having a functional surface; a connectingmember provided between and mechanically connecting the surface portionof the wiring board and the functional surface of the semiconductorchip, the connecting member establishing an interval distance thatdefines a gap between the wiring board and the semiconductor chip; aninsulating layer having an inner boundary about a periphery of thesurface portion of the wiring board; an electrode formed as part of thewiring board and positioned within the boundaries of the insulatinglayer; a sealing layer fills at least a portion of the gap between thewiring board and the semiconductor chip, and extends beyond an outerperiphery of the semiconductor chip by a lateral distance of between 0.1mm and a distance from the outer periphery of the semiconductor chip tothe electrode.
 20. The semiconductor device according to claim 19,wherein the connecting member electrically connects a wire in the wiringboard to a functional part of the functional surface.
 21. Thesemiconductor device according to claim 19, wherein the intervaldistance is greater than a thickness of the insulating layer.
 22. Thesemiconductor device according to claim 19, wherein the lateral distancethat the sealing layer extends beyond the outer periphery of thesemiconductor chip is within the inner boundary of the insulating layer.23. The semiconductor device according to claim 19, wherein the sealinglayer completely fills the gap between the wiring board and thesemiconductor chip.
 24. The semiconductor device according to claim 19,wherein the inner boundary of the insulating layer is outside the outerperiphery of the semiconductor chip.
 25. A semiconductor devicecomprising: a wiring board having a surface that is part of an upperside of the wiring board; a semiconductor chip having a functionalsurface; a connecting member provided between and extending a distancebetween the surface of the wiring board and the functional surface ofthe semiconductor chip; an insulating layer provided over a portion ofthe upper side of the wiring board and having an inner boundary that isoutside and about an outer periphery of the semiconductor chip; asealing layer fills at least a portion of a gap space between the wiringboard and the semiconductor chip, and extends beyond an outer peripheryof the semiconductor chip by a lateral distance of between 0.1 mm and adistance from the outer periphery of the semiconductor chip to an outeredge of the upper surface of the wiring board.
 26. The semiconductordevice according to claim 25, wherein the sealing layer completely fillsthe gap space between the wiring board and the semiconductor chip. 27.The semiconductor device according to claim 25, wherein the connectingmember electrically connects a wire in the wiring board to a functionalpart of the functional surface.
 28. The semiconductor device accordingto claim 25, wherein the sealing layer extends beyond the outerperiphery of the semiconductor chip by a lateral distance of between 0.1mm and a distance from the outer periphery of the semiconductor chip tothe inner boundary of the insulating layer.
 29. The semiconductor deviceaccording to claim 25, wherein the distance between the surface of thewiring board and the functional surface of the semiconductor chip is aninterval that establishes the gap space.
 30. The semiconductor deviceaccording to claim 25, wherein the connecting member electricallyconnects a functional part of the functional surface to a conductivelocation on a bottom surface of the wiring board.